Thirumalaia kaara, Nidek, 2022

Nidek, Ryosuke Matsushima, 2022, First report of the genus Thirumalaia Zettel & Laciny, 2021 (Hemiptera: Veliidae) in the Ryukyu Islands, Japan, with the description of a new species, Zootaxa 5138 (3), pp. 339-346 : 340-343

Thirumalaia kaara sp. nov.

( Table 1 , Figs. 1–12 )

Type material. HOLOTYPE: Japan: Ishigaki-jima Island: ♂ (NSMT-I-He 84328, offspring of cultured individuals, Okinawa Prefecture, Ishigaki-shi, Miyara (24°26' N 124°13' E), 3 XI 2020, R. Matsushima leg. PARATYPES: Japan: Ishigaki-jima Island : 1♂, 2♀ (NSMT-I-He 84329–84331, Okinawa Prefecture, Ishigaki-shi, Miyara, 3 XI 2020, R. Matsushima leg.; 3♂, 1♀ (NSMT-I-He 84332–84335), same data as holotype; Japan: Iriomote-jima Island : 2♀ (NSMT-I-He 84336–84337), Okinawa Prefecture, Yaeyama-gun, Taketomi-cho, Iriomote (24°22' N 123°45' E), 29 XI 2020, T. Aiso leg.

Apterous male (holotype). Body length 2.41, maximum body width 0.86; head length 0.44, head width 0.34; pronotum length 0.51, pronotum width 0.75; lengths of antennal segments I: II: III: IV = 0.37: 0.26: 0.44: 0.64; lengths of leg segments (femur, tibia, 1st tarsomere: 2nd tarsomere): fore leg: 0.61, 0.59, 0.27; middle leg: 0.73, 0.77, 0.12, 0.22; hind leg: 0.83, 1.00, 0.17, 0.25.

General coloration blackish-brown ( Fig. 1 ). Almost entire body with short, brown pubescence. Eyes dark-red, labium yellowish with black apical segment, antennae brown. Pronotum blackish-brown, anterior margin yellowish, punctures black, lateral part of anterior margin with long, silvery hairs. Legs yellowish but apices of femora, tibiae, and all tarsi dark-brown. Abdomen mainly dark-brown dorsally, gray ventrally, posterior margin of mediotergite VII and lateral margin of laterotergites orange-brown, posterior margin of mediotergite I and II with long, golden hairs. Pygophore, proctiger and paramere orange-brown to yellowish. Long, erect, brown setae on each antennal segment, inner margin of eyes and legs.

Body large, moderately stout; head length 1.29 times head width, with a longitudinal furrow. Antennae very long and slender, 0.71 times body length, antennal segments I and II thickened, antennal segment II slightly more slender and shorter than I, antennal segments III and IV longer and more slender than I and II, antennal segment III shorter than IV ( Fig. 3 ). Pronotum long, covering entire mesonotum and metanotum in middle, reaching mediotergite I; pronotum width ca. 1.4 times pronotal length, anterior margin slightly excavate and posterior margin broadly rounded, with scattered dense, dark punctures; metanotum represented by triangular lobes on lateral sides. Legs long, simple, femora slightly thickened; short apical grasping comb on fore tibia, about 0.15 times tibial length ( Figs. 4, 7 ); middle and hind legs slightly slender ( Figs. 5, 6 ). Claws preterminal.Abdomen ventrally without special modifications; laterotergites subrectangular, slightly raised; posterior of mediotergite VII excavate ( Fig. 1 ); mediotergite VIII distinctly protruding behind mediotergite VII, length 1.80 times width, subcylindrical, dorsal posterior margin slightly concave ( Fig. 8 ). Pygophore pear-like shape with truncated posterior margin in dorsal view; proctiger small, elongate, symmetrical, apex blunt, with slender, step-like lateral lobes ( Figs. 9, 10 ); paramere symmetrical, distally slender and strongly curved in lateral view, concaved at base of middle part in dorsal view, with acute, pointed apex, with long, erect setae basally ( Figs. 11, 12 ).

Apterous female. Body length 2.37, maximum body width 1.06. Color, pilosity, and structures similar to apterous male, but body stout, all femora of similar width, fore tibia lacking grasping comb, posterior corner of laterotergite VII and mediotergite VIII rounded, proctiger relatively small ( Fig. 2 ).

Macropterous. Unknown.

Diagnosis. Thirumalaia resembles some species of Baptista Distant, 1903 , Geovelia Zimmermann, 1984 and Hispidovelia Zettel, Laciny & Tran, 2021 in some characters, such as the structure of antenna and a concave anterior margin of the pronotum. Except for the B. collaris species group, males of Baptista possess the strong modifications of the forelegs and abdominal segments VI and VII. Species of the Baptista collaris group do not have those modifications; however, their protibia bears a row of stout, spine-like setae in both sexes, mediotergite VIII is posterodorsally distinctly emarginate and the parameres are distally strongly dilated ( Zettel 2004, Ye et al. 2014a). The preterminal claws distinguish T. kaara sp. nov. from species of Geovelia , which is characterized by the subterminal claws that clearly surpass the apex of tarsus ( Zimmermann 1984; Zettel & Laciny 2021). The type species of Hispidovelia , H. hispida was originally placed in Geovelia ( Ye et al. 2014b) , but preterminal claws and numerous long erect hairs distinguish it—among other characteristics—from Geovelia (Zettel et al. 2021) . Moderate eye size, long pilosity and the slender parameres differ Hispidovelia from Thirumalaia (comp. Zettel & Laciny 2021; Zettel et al. 2021).

This new species can be distinguished from T. ocularis by a relatively small body, the structure of the antenna, moderate eye size, short grasping comb and the male parameres ( Table 1 , Fig. 7 ). Body lengths of male and female T. ocularis are 2.55–2.64 and 2.80–3.00, whereas those of T. kaara sp. nov. are 2.33–2.41 and 2.37–2.46, respectively. Antennal segments III and IV of T. ocularis are similar in length; however, in T. kaara , antennal segment IV is significantly longer than III. In T. ocularis , males have a relatively long grasping comb that is about one third as long as the protibia; whereas in T. kaara sp. nov., it is one-sixth to one-seventh the length of the protibia ( Fig. 7 ). The parameres of the new species are larger and distally more slender and curved ( Figs. 11, 12 ), which differs from those of T. ocularis .

Ecological notes. The adults were collected from a small forest stream. Specifically, they were collected from small, shallow pools and stagnant areas formed between rocks near the stream bank. In Ishigaki-jima Island, this species was found sympatrically with Rhagovelia esakii Lundblad, 1937 , Pseudovelia takarai Miyamoto, 1964 and Microvelia sp. Specimens of T. kaara sp. nov. were collected at much lower elevation than T. ocularis ; T. kaara sp. nov.: 45 m and 20 m on Ishigaki-jima Island and Iriomote-jima Island, respectively; T. ocularis : 1500–2100 m.

Distribution. Japan (Okinawa Prefecture: Ishigaki-jima Island and Iriomote-jima Island) ( Fig. 13 ).

Etymology. From the dialect of Yaeyama kaara , meaning “river” where this new species inhabits. Dr. G. Thirumalai, dedicated to the genus name Thirumalaia , was a researcher of water bugs in India. This species name also refers to the Hindi kaala, meaning “black” of the body color.

Figures

FIGURE 13. Distributions of Thirumalaia species.

FIGURES. 1–2. Dorsal habitus of Thirumalaia kaara sp. nov. from Ishigaki-jima Island, Okinawa Prefecture, Japan. 1, Male (NSMT-I-He 84334); 2, female (NSMT-I-He 84335) (scale 1.0 mm).

FIGURES 3–12. Thirumalaia kaara sp. nov., apterous male. 3,Antenna; 4–6, fore leg, middle leg, hind leg, respectively; 7, apical part of fore leg with grasping comb of tibia; 8, ventral view of mediotergite VIII; 9–10, dorsal and lateral views of proctiger; 11–12, dorsal and lateral views of right paramere.